What happened, in summary

A 61-year-old woman had Stage IV EGFR-mutated lung adenocarcinoma. At presentation, imaging showed a right upper-lobe nodule, a right perihilar mass, and a right pleural effusion. She received several single-agent treatments in sequence, including erlotinib, gemcitabine, and pemetrexed, after which only minimal disease remained.

Later imaging showed that the right perihilar mass had enlarged. A repeat biopsy confirmed relapsed disease and identified the EGFR T790M mutation, so osimertinib was started.

About 1 month into osimertinib, she developed painful cut-like lesions on the tips and palms of several fingers, with dryness near the nail beds. The lesions progressed across multiple fingers and interfered with daily activities. Examination found linear ulcers about 1 cm long and areas of dry, scaly skin.

Colloidal oatmeal provided partial relief. She continued osimertinib, and the finger lesions remained bothersome but controlled with regular topical treatment.